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Article
treated with ascorbic and citric acids
Lucimara Rogéria Antoniolli (1*); Benedito Carlos Benedetti (2); Men de Sá Moreira de Souza Filho (3); Deborah dos Santos Garruti (3); Maria de Fátima Borges (3)
(1) Empresa Brasileira de Pesquisa Agropecuária (Embrapa), CNPUV, Caixa Postal 130, 95700-000 Bento Gonçalves (RS), Brasil.
(2) UNICAMP, Faculdade de Engenharia Agrícola, Caixa Postal 6011, 13083-970 Campinas (SP), Brasil.
(3)Embrapa, CNPAT, Rua Dr.a Sara Mesquita, 2270, 60511-110 Fortaleza (CE), Brasil.
(*) Corresponding author: lucimara@cnpuv.embrapa.br
Received: Dec. 6, 2011; Accepted: June 28, 2012
Abstract
The purpose of this research was to determine the shelf life of minimally processed (MP) ‘Pérola’ pineapples treated with ascor-bic acid (AA) and citric acid (CA) based on physical, chemical, sensorial and microbiological attributes. Slices were dipped into drinking water (control) or combined solutions of AA:CA (%) (1.0:0.5 and 1.0:1.0) with sodium hypochlorite (NaClO 20 mg L–1) for
30 seconds. The samples were conditioned in polyethylene terephtalate packages and stored at 4±1 °C per 13 days. The low peroxidase activity in the slices treated with antioxidant combinations was related to low pH values observed in these samples. The treatments 1.0:0.5 and 1.0:1.0 (AA:CA, %) favored maintenance of the initial a* values and avoided the pulp browning. The ascorbic acid increased more than double on the 2nd day in the treated slices. By the 4th day the CO
2 values suggested a higher
respiratory activity in the slices treated with anti-browning compounds. The antioxidant treatments did not produce detectable
residual flavors in the MP pineapple. Regardless of microbiological safety during the 13 days of cold storage, the control slices can be kept by 6 days, afterwards the color and dehydration become strong enough to affect the appearance. On the other
hand, MP ‘Pérola’ pineapples treated with 1.0:0.5 (AA:CA, %) and NaClO (20 mg L–1) can be stored for 8 days at 4±1 ºC, which
represents the extension of the shelf life in 2 days. After this period the overripe odor starts to develop. Key words:Ananas comosus, minimal processing, enzymatic browning, residual flavor, microbiological safety.
Vida útil de abacaxis minimamente processados tratados com ácido ascórbico e ácido cítrico
Resumo
Procurou-se determinar a vida útil de abacaxis ‘Pérola’ minimamente processados (MP), tratados com ácido ascórbico (AA) e ácido cítrico (AC), com base nos atributos físicos, químicos, sensoriais e microbiológicos. As fatias foram imersas em água (controle) ou em soluções combinadas de AA:AC (%) (1,0:0,5 e 1,0:1,0) com adição de hipoclorito de sódio (NaOCl 20 mg L–1),
durante 30 segundos. As amostras foram acondicionadas em embalagens de polietileno tereftalato e mantidas à tempera -tura de 4±1 °C durante 13 dias. A baixa atividade da peroxidase nas fatias tratadas foi relacionada aos baixos valores de pH observados nessas amostras. Os tratamentos 1,0:0,5 e 1,0:1,0 (AA:AC, %) favoreceram a manutenção dos valores iniciais de a* e evitaram o escurecimento da polpa. A concentração de ácido ascórbico aumentou mais que o dobro, no 2.° dia, nas fatias tratadas. Os valores de CO2 observados no 4.° dia sugeriram a ocorrência de maior atividade respiratória nas fatias tratadas com os compostos antioxidantes. Os tratamentos antioxidantes não produziram sabor e odor residuais no abacaxi MP. Apesar de comprovada a segurança microbiológica durante os 13 dias de armazenamento, as fatias-controle podem ser mantidas por seis dias, uma vez que o escurecimento e o aspecto desidratado prejudicam a aparência do produto após esse período. Abacaxis ‘Pérola’ MP tratados com 1.0:0.5 (AA:AC, %) e NaOCl (20 mg L–1) podem ser armazenados por 8 dias a 4±1 ºC, o que
representa o prolongamento da vida útil em dois dias. Após esse período, o odor de sobremaduro começa a se desenvolver.
Palavras-chave: Ananas comosus, processamento mínimo, escurecimento enzimático, sabor residual, segurança microbiológica.
1. INTRODUCTION
The supply of minimally processed (MP) products has been increased considerably in the late years. Frequently, however, the quality of such products is still unsatisfac-tory. Pineapples stand out among tropical fruits that have potential to be commercialized as a ready-to-eat product
processes (Rolle and Chism, 1987). The main enzymes responsible for tissue browning in fruits are polyphenol oxidase (PPO) and peroxidase (POD) (Gonçalves, 2000). Das et al. (1997) did not observe polyphenol oxidase activity in pineapple juice. Likewise, Brito et al. (2007) reported no PPO activity in homogenized pineapple pulp of Pérola, Smooth Cayenne and IAC Gomo-de-Mel cultivars. POD is involved in multiple deteriorative changes affecting flavor, texture, color and nutrition in processed fruits and vegeta-bles. POD performs a more important role in the browning process than PPO in pineapples, as previously found in ji-cama roots (Aquino-Bolaños and Mercado-Silva, 2004). The use of browning inhibitors in minimally pro-cessed products is restricted to compounds that neither contribute to toxicity risk nor interfere in flavor (Sapers, 1993). Compounds used to inhibit browning include ascorbic acid (AA), which decreases pH and is a reducing agent. In addition, this agent is cheap and safe for human consumption (Sapers, 1993). A more effective preserva-tion of color can be achieved by using a combinapreserva-tion of an antioxidant agent (e.g. AA) and an acidulant (e.g. cit-ric acid, CA) (Sapers and Douglas, 1987; Laurila et al., 1998; Ahvenainen, 2000). Additionally, this kind of treatment can be considered a way to enrich fruit tissue in AA (Cocci et al., 2006). As reported by Weller et al. (1997), when slices of starfruit were treated in 1.0 or 2.5% CA and 0.25% AA solution, they presented less browning than the control samples. Combinations of ascorbic acid (0.5% to 1.0%) and citric acid (0.2% to 1.0%) have been described as efficient for preventing browning in mini-mally processed apple (Artés et al., 1998).
The objective of this research was to determine the shelf life of minimally processed ‘Pérola’ pineapples treat-ed with ascorbic and citric acids bastreat-ed on physical, chemi-cal, sensorial and microbiological attributes.
2. MATERIAL AND METHODS
Pineapples (Ananas comosus L. Merril cv. Pérola) were harvested
from a commercial field located in Touros (Rio Grande do Norte State, Northeast of Brazil). Fruit were selected accord-ing to the size and the skin color (fruits completely green and with a yellow fruitlet center, corresponding to stages 1 and 2 of the Classification Standards of Pineapples; CQH, 2003). The crowns were cut at about 30 mm from the fruit apical re-gion. Fruit were washed with water and neutral detergent and
disinfected with a NaClO solution (200 mg L–1) for 2 min
(Antoniolli et al., 2005). Fruit were conditioned in washed
and disinfected (200 mg L–1 NaClO solution) plastic boxes and
kept at 12±1 ºC for approximately 24 h. After that, they were
mechanically peeled and manually sliced. The slices were cut at approximately 10 mm thickness and their cores were removed.
The slices were dipped in water (control) or different com-bined solutions of ascorbic acid and citric acid for 30 seconds.
Based on the preliminaries results, treatments consisted of the combinations 1.0:0.5 and 1.0:1.0 (AA:CA, %). Both
solu-tions, including control, had NaClO 20 mg L–1 added and
they were kept at 10 ºC. All the chemicals used were of analyti-cal grade (Sigma Chemianalyti-cal Co.). The liquid excess was drained for 2 min. The equipment and utensils were disinfected with
200 mg L–1 NaClO solution to prevent crossed
contamina-tion. Disposable gloves, masks and head wear were used with the same intention. The processing was carried out in refriger-ated conditions, with temperatures from 12 to 15 ºC.
The pineapple slices were conditioned in polyeth-ylene terephthalate (PET) packages previously sanitized
with NaClO solution (20 mg L–1), and stored at 4±1 ºC
per 13 days. The PET packages were sealed by pressure. Every two days, the fruits were evaluated regarding to a) pH: in the homogenized samples; b) peroxidase
ac-tivity (U g–1 min–1): determined according to the
meth-odology of Khan and Robinson (1994); c) pulp color: measured with a Minolta Chromameter (Model CR-300) in the CIE L*a*b* mode. Although there is a reference (González-Aguilar et al., 2004) for assessing pulp browning in minimally processed pineapples by analyzing L* (lightness loss) and b* (yellowness loss) parameters, the evaluation was carried out using the L* and a* parameters, which are recommended for apples (Artés et al., 1998), since they were more efficient in detecting browning in
preliminary assays; d) ascorbic acid content (mg 100 g–1):
determined according to Carvalho et al. (1990). In
ad-dition, CO2 was measured along the storage period and
consisted in conditioning slices in hermetically sealed containers (1.5 L), which were fitted with a rubber sep-tum, allowing for headspace gas sampling. Gas samples were taken every day and injected in a gas chromatograph
(CG DANI 86.10) fitted with TCD detector for CO2 and
FID detector for ethylene. A Porapak N column was used with 4.0 m length and 3.175 mm diameter, operated at constant temperature of 60 ºC. Hydrogen was used as
carrier gas at a flow rate of 30 mL min–1. Carbon dioxide
was quantified by calibration with a standard of 5% CO2.
The slices were evaluated for residual flavor
af-ter approximately 15 hours of storage at 4±1 ºC. The
‘Difference-of-Control’ test was carried out by a non-trained sensory panel with 30 assessors. This test is used to determine perceptive differences between each treatment and a standard (non-treated pineapple) (Ferreira et al., 2000). The presence of total (35 ºC) and thermotoler-ant (44.5 to 45.5 ºC) coliforms in the fresh-cut pineapple was evaluated on day 0 (initial). Mesophilic aerobic, mold and yeast counts were made at 0, 1, 4, 7, 10 and 13 days. Analyses were carried out according to the methodology described by Silva et al. (2007) and Downes and Ito (2001). Mesophilic aerobic, mold and yeast populations
were expressed by log CFU g–1.
evaluated at 1, 4, 6, 8 and 11 days, according to the main attributes that indicate loss quality in minimally processed pineapple: color (browning), translucency, dehydration appearance, and overripe odor and flavor. The assessment was performed by applying a descrip-tive analysis with a panel of 9 trained assessors to spe-cifically evaluate the aforementioned attributes. The Quantitative Descriptive Analysis (QDA) provides a complete description and quantification of the sensory properties of a product, representing one of the most complete and sophisticated methods for characterizing important sensory attributes (Stone et al., 1974). A 9-cm non-structured hedonic scale was used.
All the experiments were performed in an entirely randomized design, and the interaction between treat-ment and time was evaluated with three replicates. Data was submitted to a variance analysis (ANOVA), and the means were compared through Tukey multiple range test at p ≤ 0.05. The means obtained in the sensory analysis were analyzed using the Dunnet test, at p ≤ 0.05. The values of mesophilic aerobic, mold and yeast counts were transformed into log (x), submitted to a variance analysis (ANOVA) and the means were compared through Tukey multiple range test at p ≤ 0.05.
3. RESULTS AND DISCUSSION
Physical, chemical, sensorial and
microbiological parameters as indices to determine the best anti-browning treatment
The pH values in the MP pineapples submitted to treat-ments 1.0:0.5 and 1.0:1.0 (AA:CA, %) were statistically lower than the control, but no significant difference was detected between the antioxidant treatments (Figure 1a). Such results are in accordance to the previous data on higher pH in non-treated pineapple slices, as compared to the slices submitted to eight different combinations
of ascorbic and citric acids, during 8 days at 4±1 ºC.
Independent of the treatment, the pH of the MP pine-apple decreased during the 12 days of storage (Figure 1b).
From the 6th day on, the pH values were significantly
low-er than those obslow-erved at the beginning of the explow-eriment
(day 0), and reached 3.96 on the 12th day of storage.
On the 2nd and 6th days of storage, the
peroxi-dase activity of the MP pineapple treated with 1.0:0.5 (AA:CA, %) was lower than that one of the control slices (Figure 2), but it did not differ from the MP treated with 1.0:1.0 (AA:CA, %). The drastic decrease in peroxidase activity in the control fruit samples, which was observed
on the 8th day, narrowed the differences among the
treat-ments and no significant difference was detected among the two treatments and the control. During the experi-mental period, the MP fruit samples submitted to the ascorbic and citric acid treatments tended to demonstrate little variation in peroxidase activity, and there was no difference during the entire evaluation period. The low peroxidase activity in the MP fruits treated with antioxi-dant combinations, which was observed mainly until the
6th day, was possibly related to low pH values. According
to Burnette (1977), acidification of peroxidase causes a pronounced change in the protein from the native state to the reversible denatured state. It is known there is an inherent gradient of maturation from the basal to apical area in the pineapple fruit (Dull, 1971) and an increase of the peroxidase solubility as a result of the fruit matura-tion advance (Mello and Clemente, 1996). Therefore, it is possible that the accentuated reduction in the
peroxi-dase activity observed in the control, on the 8th day, could
be due to the ripening degree dissimilarity between these samples and the others in the experiment. According to Brito et al. (2007), the peroxidase activities in the basal, medium and apical areas of the ‘Pérola’ pineapple were
estimated as 6091, 5099, and 5683 U g–1, respectively.
The addition of ascorbic and citric acids did not af-fect the L* color of the MP pineapple, which ranged from 61.91 to 66.05 for 12 days of storage (data not showed). In the control, there was a gradual increase in the a*
pa-rameter of pulp color, reaching -0.09 on the 8th day of
Figure 1. Values of pH in MP ‘Pérola’ pineapple treated with two combinations of ascorbic acid (AA) and citric acid (CA) (a), and stored at 4±1 ºC for 12 days (b). LSD: Least Significant Difference (p ≤ 0.05).
pH
1.0:0.5 0.0:0.0 (Control) 4.12
Treatments (AA:CA%) 4.10
4.08 4.06 4.04 4.02 4.00 3.98 3.96 3.94
1.0:1.0 |LSD=0.04
pH
Days
0 2 4 6 8 10 12
4.12 4.10 4.08 4.06 4.04 4.02 4.00 3.98 3.96 3.94
|LSD=0.08
storage and, afterwards, remaining without significant changes. The chromatic coordinate a* varies from nega-tive values which indicate green to posinega-tive ones that in-dicate red/magenta. The changes observed in this coor-dinate in the non-treated slices may have contributed to brownish tones noticed in the sensorial test after 8 days of storage. During the entire evaluation period, the slices
treated with antioxidant combinations did not show sig-nificant differences between treatments (Figure 3). As previously observed, the treatments 1.0:0.5 and 1.0:1.0 (AA:CA, %) favored maintenance of the initial a* values, therefore avoiding pulp browning during the entire evalu-ation period. Furthermore, Sapers and Douglas (1987) and Cocci et al. (2006) verified an effective inhibition of browning in fresh-cut apples treated with solutions con-taining ascorbic and citric acids.
The non-treated MP pineapple showed the highest oscillations in ascorbic acid contents during the storage period. In the slices treated with antioxidants, the
ascor-bic acid increased more than double on the 2nd day, and
on the 4th day it decreased to values that were statistically
equal to the control. Thereafter, the decrease in ascorbic acid content continued in a moderate manner in the pineapple slices treated with 1.0:0.5 (AA:CA, %), and it was significantly higher than that one of the control on
the 10th and 12th days (Figure 4). The rapid increase in
ascorbic acid at the beginning of storage was also observed by Carvalho and Lima (2002) on MP kiwi treated with ascorbic acid solution (1%). Cocci et al. (2006) ob-served that apple slices treated with 1.0:1.0 (AA:CA, %) showed initial values of about 20-fold higher than those of non-dipped slices, due to AA uptake as a result of the anti-browning treatment. Similarly, the values obtained by authors decreased after 1 day of storage (of 60-80%). In spite of the decrease in ascorbic acid content in the treated slices, the anti-browning treatments promoted the enrichment of the fruit. In addition, Cocci et al. (2006) showed that the dipping of fresh-cut apples in a solution of 1.0:1.0 (AA:CA, %) resulted in a detectable enriching effect in AA content until the sixth day of cold storage.
Until the 3rd day of cold storage, there was no
signifi-cant difference in the CO2 concentration, independent
of the treatment (Figure 5). On the 3rd day, the CO
2
con-centration started to increase quickly, and by the 4th day
it reached the highest values in the flasks containing slices treated with 1.0:1.0 (AA:CA, %), followed by those treated
Figure 5. Concentration of CO2 (%) inside flasks containing MP ‘Pérola’ pineapple treated with two combinations of ascorbic acid (AA) and citric acid (CA), and stored at 4±1 ºC for 12 days. LSD: Least Significant Difference (p ≤ 0.05).
CO
2
(%)
2.5
Days 2.0
1.5 1.0 0.5 0.0
|LSD=0.73
0 1 2 3 4 5 6 7 8 9 10 11 12
0.0:0.0 (Control) 1.0:0.5 (AA:CA%) 1.0:1.0 (AA:CA%) 3.5
3.0
Figure 2. Peroxidase activity in MP ‘Pérola’ pineapple treated with two combinations of ascorbic acid (AA) and citric acid (CA), and stored at 4±1 ºC for 12 days. LSD: Least Significant Difference (p ≤ 0.05).
P
eroxidase activity (U g
-1 min
-1) 5000
Days 4000
3000 2000 1000 0
|LSD=1259.34
0 2 4 6 8 10 12
0.0:0.0 (Control) 1.0:0.5 (AA:CA%) 1.0:1.0 (AA:CA%)
Figure 3. Fruit pulp color (a* value) of MP ‘Pérola’ pineapple treated with two combinations of ascorbic acid (AA) and citric acid (CA), and stored at 4±1 ºC for 12 days. LSD: Least Significant Difference (p ≤ 0.05).
Pulp color (a* value)
0.0
Days
-0.5 -1.0 -1.5 -2.0 -2.5
|LSD=0.48
0 2 4 6 8 10 12
0.0:0.0 (Control) 1.0:0.5 (AA:CA%) 1.0:1.0 (AA:CA%)
Figure 4. Ascorbic acid content in MP ‘Pérola’ pineapple treated with two combinations of ascorbic acid (AA) and citric acid (CA), and stored at 4±1 ºC for 12 days. LSD: Least Significant Difference (p ≤ 0.05).
Ascorbic acid (mg 100g
-1)
70
Days 60
50 40 30 20
|LSD=12.72
0 2 4 6 8 10 12
0.0:0.0 (Control) 1.0:0.5 (AA:CA%) 1.0:1.0 (AA:CA%) 90
with 1.0:0.5 (AA:CA, %) and by the control. Increased
CO2 levels were maintained until the end of the cold
stor-age. These results suggest a higher respiratory activity in slices treated with anti-browning compounds, which is in agreement with the reported higher metabolic activity in fresh-cut potatoes after application of citric and ascorbic acids (Rocculi et al., 2007). It is possible that the differ-ences of metabolic activity between the two treatments were induced by the increase in citric acid concentration, considering that the ascorbic acid concentration was kept constant. These results indicate that the exogenous organic acids were absorbed by the plant tissues and, possibly, the imported citric acid affected the reactions of the tricarbox-ylic acid cycle (TCA), resulting in a respiratory increase.
In the sensory tests, no significant differences were observed between the treatments and the control, indi-cating that the antioxidant treatments 1.0:0.5, 1.0:1.0 (AA:CA, %) did not produce detectable residual flavors in the minimally processed pineapple (Figure 6).
Total and thermotolerant coliforms were not de-tected in the pineapple samples evaluated at the be-ginning of the experiment (day 0), suggesting absence of these microorganisms in the raw material, and indi-cating the processing was performed in adequate hy-gienic-sanitary conditions. Endophytic population of mesophilic aerobic in the pineapple (day 0) was 4.65
log CFU g–1 and it showed a gradual increase in the
first days of storage. On the 4th day, these populations
were estimated as 106 CFU g–1 in the MP fruit
sam-ples submitted to diverse treatments, and no signifi-cant difference was detected among them (Figure 7).
Similar responses were observed on the 7th day, but
the values were lower than the previous ones, and they were estimated as 5.34, 4.41, and 4.56 log CFU
g–1 in slices treated with 1.0:0.5, 1.0:1.0 (AA:CA, %)
and in the control, respectively. The reduction can be attributed to adverse conditions of the environ-ment, especially the pH reduction (Figure 1b) which, on the other hand, favored the increase of mold and
yeast populations (Figure 8). On the 10th day, the
largest populations of mesophilic aerobic microorgan-isms were observed in the MP pineapple treated with 1.0:0.5 (AA:CA, %), and the smallest populations were found in samples treated with 1.0:1.0 (AA: CA, %). The control slices did not differ from both treatments.
On the 13th day of storage, no significant difference
was detected in the microorganism populations of the two treatments and the control. In general, the endo-phytic populations of mesophilic aerobic microorgan-isms present in the MP pineapple were in a range of
104 e 106 CFU g–1 during the entire evaluation period,
and the largest populations were observed on the 4th
day of storage (Figure 7).
Variations in mold and yeast populations in the MP pineapple were not significant among the treat-ments. Estimates of these microorganism populations
were in a range of 103 to 104 CFU g–1, and no
signifi-cant difference was detected during the 13 days of stor-age (Figure 8). Pinheiro et al. (2005) found mold and
yeast populations from 2.7x102 to 1.9x107 CFU g–1 in
samples of MP pineapple collected from supermarkets in Fortaleza, CE, Brazil.
Figure 7. Mesophilic aerobic microorganisms (MAM) in MP ‘Pérola’ pineapple treated with two combinations of ascorbic acid (AA) and citric acid (CA), and stored at 4±1 ºC for 13 days. LSD: Least Significant Difference (p ≤ 0.05).
MAM
(log CFUg
1)
5.5
Days 5.0
4.5 4.0 3.5 3.0
|LSD=1.18
0 2 4 6 8 10 12
0.0:0.0 (Control) 1.0:0.5 (AA:CA%) 1.0:1.0 (AA:CA%) 6.5
6.0 7.0
Figure 8. Mold and yeast populations in MP ‘Pérola’
pineapple, during 13 days at 4±1 ºC. LSD: Least Significant Difference (p ≤0.05).
Figure 6. Residual taste in MP ‘Pérola’ pineapple resulting from treatments with two combinations of ascorbic acid (AA) and citric acid (CA). LSD: Least Significant Difference (p ≤ 0.05).
Mold and y
east (log CFU g
-1)
Days 3.8
3.7
3.6
|LSD=1.18
0 2 4 6 8 10 12
4.0
3.9 4.1
Residual taste
(diff
erence degree)
1.0:0.5
0.0:0.0 (Control)
2.5
Treatments (AA:CA%)
2.0
1.5 1.0
0.5 0.0
The main problem of fresh-cut pineapple is not mi-crobiological decay (O’Connor-Shaw et al., 1994). It is possible the microflora of minimally processed fruit originates from within fruit tissue as a result of prehar-vest contamination (Antoniolli et al., 2005). Actually, Martínez-Ferrer and Harper (2005) stated that mini-mally processed fruit carry their natural microflora and
may have about 104-105 CFU g–1.
In general, the ascorbic and citric acids did not af-fect the population growth rates of mesophilic aerobic, molds and yeasts. The little changes in these populations were possibly related to the efficiency of the whole fruit
sanitization and the addition of NaClO (20 mg L–1) to
the solutions used for the immersion of MP pineapples.
Sensorial parameters as indices to
determine shelf life of minimally processed pineapples treated with the best anti-browning treatment
Based on the obtained results, the lowest concentration of antioxidant compounds was chosen for determining the shelf life of the MP ‘Pérola’ pineapple, on the basis of a descriptive analysis of the sensory attributes of quality. It was considered that an additive, even if natural, should be used in a level that guarantees the preservation of fruit original characteristics.
As shown in the sensory profile of the non-treated slices, color was the most changed attribute (4.2), fol-lowed by the dehydrated appearance (4.1), odor (2.8), translucency (2.7), and flavor (2.0), which were more
evident on the 8th day and afterwards. At the end of the
storage, it was observed that the alterations in color (6.8) and in dehydrated appearance (5.1) prevailed over trans-lucency (4.6) and odor (4.4) alterations. The levels of
overripe pineapple flavor remained similar to those
ob-served on the 8th evaluation day (Figure 9a). In the slices
treated with 1.0:0.5 (AA:CA, %), alterations of these at-tributes were approximately 2.0, on the scale, and they
remained practically imperceptible until the 8th day. On
the 11th day of 1.0:0.5 (AA:CA, %) treatment, the odor
was the most altered attribute (3.8), however, it was lower than the control (Figure 9b). Spanier et al. (1998) exam-ined the effect of cold storage (4 ºC) on the flavor volatile profile of fresh-cut pineapples and found that unpleasant odors and volatiles such as fermented, cheesy, sour dough, alcohol, and oily showed dramatic increases and masked the more desirable pineapple flavor.
Regardless of microbiological safety during the 13 days of cold storage, the control slices can be kept by 6 days, af-terwards the color and dehydration become strong enough to affect the appearance. On the other hand, minimally processed pineapples treated with antioxidants should have their shelf life restricted to 8 days, because after this period the overripe odor starts to develop.
4. CONCLUSION
Minimally processed ‘Pérola’ pineapple submitted to im-mersion treatment in 1.0:0.5 (AA:CA, %) with NaClO
(20 mg L–1) can be stored for 8 days at 4±1 ºC, which
represents the extension of the shelf life in 2 days.
ACKNOWLEDGEMENTS
This research received financial support from the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) – Brazil and Prodetab / World Bank. The authors thank Claísa A. Silva de Freitas for her technical contributions to this research.
Figure 9. Descriptive analysis of MP ‘Pérola’ pineapple treated with two combinations of ascorbic acid (AA) and citric acid (CA), and stored at 4±1 ºC for 11 days. (a) Control (non-treated); (b) 1.0:0.5 (AA:AC, %). (Mean values).
7 6 5
4 3 2
Odor
0
Translucent Flavor
Dehydrated appearance Color
(a)
1
7 6 5 4 3 2
Odor
0
Translucent Flavor
Dehydrated appearance Color
(b)
1 1 day
4 days 6 days 8 days 11 days
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